<!DOCTYPE html>
<html lang="en">
    <head>
        <meta charset="UTF-8">
        <title>边框内圆角</title>
        <style>
            body {
                border: 1em solid transparent;
                padding: 2em;
            }

            .div {
                width: 15em;
                height: 8em;
                word-wrap: break-word;
            }

            .inner-rounding {
                margin-left: 1em;

                padding: 10px;
                background: tan;
                outline: 1em solid #655;
                box-shadow: 0 0 0 .8em #655;
                border-radius: .5em;
            }

            .wrapper {
                display: inline-block;
                background: #655;
                padding: 1em;
            }

            .inner {
                padding: 10px;
                background: tan;
                border-radius: .5em;
            }

            hr {
                margin: 20px 0;
            }
        </style>
    </head>
    <body>
        <div class="div inner-rounding">
            box-shadow + outline 实现.
            outline 不会跟着圆角走(以后浏览器标准应该会跟着圆角走), 而 box-shadow 会跟着圆角走
        </div>
        <hr>
        <div class="wrapper">
            <div class="inner div">
                2 个 div 实现
            </div>
        </div>
    </body>
</html>